My daughter is just so difficult.

[Namechangenurseryconcerns]

I feel like I'm losing it. DD is 7. She has never been easy at any stage but recently everything has been a battle.
She whinges and complains about pretty much everything-getting dressed, eating, school work, washing, exercise, going to bed... Nothing is ever good enough and is met with groans and tears.
I've tried rewarding good behaviour but mainly I end up getting cross which is obviously no good for anyone. It's like she just wants to push me until I lose my temper and then everything will reset for a while until the next obstacle.

She would be quite happy to sit watching tv or listening to audio books, eating crap and going to bed at midnight but life's not like that!! Especially in term time.

I don't even know what I'm asking. I just think I've lost my way with her and need some help getting back on track.

Does she have a set routine? In that she knows as soon as she's finished breakfast she has to go and get ready for school and can then have 10 mins of screen time? Set bed times? It might help to have a very strong routine with plenty of down time.
Maybe use half term to have a 'grown up' conversation with her about her not being happy. And that you hate feeling cross with her. Ask her for some suggestions to make homelife happier for you both. Agree to lots of down time and plenty of time doing things together.
Tell her you're prepared to treat her like the older child she is becoming, but in return she has to behave like one.

Yes we do have a set routine. But as the battles are as predictable as the routine I think we might need to tweak it.
We have had a very busy half term so you are probably right that she needs some down time. It goes against my nature as I prefer to use free time to be busy and active but I recognise that she may think differently!
I try to do nice things with her but it often becomes a case of 'give her an inch and she takes a mile'
I think I need to re read how to talk ...

It's bloody hard, isn't it! My DD is 8. I get that working mother guilt that I have to do chores eves and weekends (which she helps with), so try to make sure we do loads of activities, walks, outings etc. Then I wonder why she's knackered and whingey!

Try love bombing.
You take her away for a day, just the two of you and spend that time totally focused on your girl doing things that you know she'd enjoy.
Its all about re-bonding and it does work. You could take her to the zoo have lunch out, a quick twirl around Claire's Accessories (they seem to love that shop at that age!) finish off the day with a trip to the cinema; the most important aspect being that your focus is solely on your daughter and she gets to feel special. Worth a try o/p.